Input lag in textbox

Mark Huisinga 1

We have a mobile sales application which is primarily used on a tablet. Our customers use this to enter orders while en route at various customers.
Input is done by typing on the onscreen keyboard in various fields (itemcode, quantity, price etc.)
Sometimes during order entry we notice a delay between pressing a key on the on screen keyboard and seeing it in the textbox. So for example the customer enters 'RRN' but only 'RR' is showing in te textbox. As soon as they press N again (or any other key) the lagging key is also shown, so the textbox now reads 'RRNN'. It is also possible to wait for the key to show up by itself but that can take up to 10seconds.

We trap key events using the CoreWindow.Dispatcher.AcceleratorKeyActivated

As you can imagine this is very frustrating for our customers.

Any ideas ?

Thanks, Mark

Fay Wang - MSFT 5,221 Reputation points

2020-01-17T03:24:41.697+00:00

What are you doing in the CoreWindow.Dispatcher.AcceleratorKeyActivated event? And can you please provide a simple sample that can be reproduced this input delay issue?
Mark Huisinga 1 Reputation point

2020-01-21T16:58:45.967+00:00

I have created a sample project that can be used to reproduce the problem. How do I get this project to you ?
Fay Wang - MSFT 5,221 Reputation points

2020-01-23T08:06:18.143+00:00

You can upload the sample to github or oneDrive, etc where we can download it.
Mark Huisinga 1 Reputation point

2020-01-23T09:10:50.92+00:00

I have just added it to Github. Repository is mhuisinga/KeyboardTest

thanks!
Fay Wang - MSFT 5,221 Reputation points

2020-01-28T07:16:41.993+00:00

I tested your project in my surface book and it worked well, there is no delay between pressing a key on the on screen keyboard and seeing it in the textbox. What is your device? And if you tested it in another machine, will the same issue occur?
Mark Huisinga 1 Reputation point

2020-01-30T07:47:01.77+00:00

I think the cpu of the surface is more then fast enough for this not to be able to replicate it.

I have tested it on Newland NQ-800 and Newland NQ-800 II. Both of these are running an intel Atom, the version II the Atom x5-z8350 which is the faster one.

Using the onscreen keyboard I only notice the behaviour in our full application. And then only after some time. So in order to figure out where the problem was I created the test application. But since this is a much lighter application I could not simulate the problem by typing on the device.

I now use teamviewer from a pc to connect to the tablet and type on the pc. So the onscreen keyboard is not used at all. And then after trying a few times I get the same effect.

Basically the key is there but is not sent to the application. And on the next keypress both keys are send. If you want I can send you a video. Or give you access to our full application.
Fay Wang - MSFT 5,221 Reputation points

2020-02-03T09:09:03.357+00:00

OK, you can send the video and full application for us to test. But before you send them, please ensure that sensitive or private information has been removed.
Mark Huisinga 1 Reputation point

2020-02-06T11:00:51.9+00:00

Hi, I need to send a username and password to you in able to allow you to access the application. Is there a way I can send a PM to you ?
Amy Peng-MSFT 251 Reputation points Microsoft Employee

2020-02-07T09:51:25.357+00:00

Thanks very much for your cooperation. Based on your description, it sounds like that this issue occurs randomly. May I know which OS version that you have met this issue? Since forum is the public place, it is not allowed to share your username/password and your full project if it contains sensitive information and we can not reproduce this issue in Windows 10 1909 as well, so I suggest that you might need to open a support ticket for this. You will get 1:1 support on that. Please kindly note that your support ticket will be free if it is Microsoft's issue. Thanks.
Mark Huisinga 1 Reputation point

2020-02-13T10:25:02.51+00:00

We have this issue since version 1803 although it looks as we're having more issues in later versions.
We'll start a support ticket to get this resolved. Thanks.

1 answer

Steve Wood 56 Reputation points

2020-02-10T22:32:00.523+00:00

When a TextBox has focus it traps key events for you. Just add event handlers for the PreviewKeyDown and PreviewKeyUp events.
Please sign in to rate this answer.

0 comments No comments
Sign in to comment

Use comments to ask for clarification, additional information, or improvements to the question.

Share via

Input lag in textbox

1 answer

Your answer